The present invention relates to battery chargers, and more particularly, to a liquid cooled metallic inductive charging probe for use in high power battery charging apparatus.
The assignee of the present invention designs, develops and manufactures inductive charging systems for use in charging electric batteries of electric vehicles, and the like. The charging system employs a charge port comprising secondary windings and core that form a secondary of a transformer installed in the electric vehicle, and a charge coupler or probe comprising a primary winding and a core that form a primary of a transformer that is coupled to a power source and which is inserted into the charge port to charge the vehicle batteries. Charging of the batteries is done at high frequency and at high charging rates. Consequently, there is a great deal of heat buildup in the charge probe. The probe must be removed front the charge port by a user once charging is complete, and the touch temperature of the probe is a concern.
Four different approaches may be used to implement thermal management of inductive charge coupler port temperatures. The first approach is to rely on conduction of heat from the primary winding and core across an air gap interface to on-board heat exchangers having cooling air circulated by charge port fans. This approach works for systems operating from about 6 kw to 10 kw charging rates. The second approach is to route chilled air from off-board refrigeration unit through the coupler. This approach works for systems operating at charge rates from about 20 kw to 25 kw. The third approach is to use a plastic or ceramic heat exchanger that does not interact with the magnetic fields produced by the charging system. However, this approach has poor thermal transfer characteristics. The fourth approach is to use a metallic heat exchanger, that interacts with the magnetic field, resulting in a degree of proximity losses, depending on its location in the winding.
Although on-board air or liquid from vehicle cooling systems may become available in some near term electric vehicles, it cannot be universally guaranteed. Furthermore, at charge rates above 25 kw, the increase in size and power consumption of fans and air chillers becomes prohibitive.
Therefore, it is an objective of the present invention to provide for an improved liquid cooled metallic inductive charging probe for use in high power battery charging apparatus.